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III-Nitride Dry Etching - Comparison of Inductively Coupled Plasma Chemistries

Description: A systematic study of the etch characteristics of GaN, AlN and InN has been performed with boron halides- (BI{sub 3} and BBr{sub 3}) and interhalogen- (ICl and IBr) based Inductively Coupled Plasmas. Maximum etch selectivities of -100:1 were achieved for InN over both GaN and AlN in the BI{sub 3} mixtures due to the relatively high volatility of the InN etch products and the lower bond strength of InN. Maximum selectivies of- 14 for InN over GaN and >25 for InN over AlN were obtained with ICl a… more
Date: November 10, 1998
Creator: Abernathy, C.R.; Cho, H.; Donovan, S.M.; Hahn, Y-B.; Han, J.; Hays, D.C. et al.
Partner: UNT Libraries Government Documents Department
open access

Pulse length dependence of laser conditioning and bulk damage in KD2PO4

Description: An experimental technique has been developed to measure the damage density {rho}({phi}) variation with fluence from scatter maps of bulk damage sites in plates of KD{sub 2}PO{sub 4} (DKDP) crystals combined with calibrated images of the damaging beam's spatial profile. Unconditioned bulk damage in tripler-cut DKDP crystals has been studied using 351 nm (3 {omega}) light at pulse lengths of 0.055, 0.091, 0.30, 0.86, 2.6, and 10 ns. It is found that there is less scatter due to damage at fixed fl… more
Date: November 10, 2004
Creator: Adams, J. J.; Weiland, T. L.; Stanley, J. R.; Sell, W. D.; Luthi, R. L.; Vickers, J. L. et al.
Partner: UNT Libraries Government Documents Department
open access

Reciprocal-Space Analysis of Compositional Modulation in Short-Period Superlattices Using Position-Sensitive X-Ray Detection

Description: Epitaxial growth of AlAs-InAs short-period superlattices on (001) InP can lead to heterostructures exhibiting strong, quasi-periodic, lateral modulation of the alloy composition; transverse satellites arise in reciprocal space as a signature of the compositional modulation. Using an x-ray diffractometer equipped with a position-sensitive x-ray detector, we demonstrate reciprocal-space mapping of these satellites as an efficient, nondestructive means for detecting and characterizing the occurren… more
Date: November 10, 1998
Creator: Ahrenkiel, S. P.; Follstaedt, D. M.; Lee, S. R.; Millunchick, J. M.; Norman, A. G.; Reno, J. L. et al.
Partner: UNT Libraries Government Documents Department
open access

Nanometer-Scale Compositional Structure in III-V Semiconductor Heterostructures Characterized by Scanning Tunneling Microscopy

Description: Nanometer-scale compositional structure in InAsxP1.InNYAsxPl.x-Y/InP, grown by gas-source molecular-beam epitaxy and in InAsl-xPJkAsl$b#InAs heterostructures heterostructures grown by metal-organic chemical vapor deposition has been characterized using cross-sectional scanning tunneling microscopy. InAsxP1-x alloy layers are found to contain As-rich and P-rich clusters with boundaries formed preferentially within (T 11) and (111) crystal planes. Similar compositional structure is observed withi… more
Date: November 10, 1998
Creator: Allerman, A. A.; Bi, W. G.; Biefeld, R. M.; Tu, C. W.; Yu, E. T. & Zuo, S. L.
Partner: UNT Libraries Government Documents Department
open access

Experiments with polymer coated microspheres irradiated by the Shiva laser system

Description: Polymer coated spherical targets have been irradiated by the Shiva laser system in an effort to compress the contained 10 mg/cc DT fuel to super liquid densities. Glass microspheres of 140 ..mu..m ID and 5 ..mu..m wall thickness with polymer coatings 15 ..mu..m to 100 ..mu..m thick have been irradiated with laser pulses of 4 kilojoules in 200 psec FWHM. Target performance was diagnosed with neutron yield measurements, radiochemistry, Argon line imaging, and x-ray imaging techniques. Ball in pla… more
Date: November 10, 1979
Creator: Auerbach, J. M.; Manes, K. R. & Matthews, D. L.
Partner: UNT Libraries Government Documents Department
open access

C.A.S.I.S. Workshop 2003 Abstract Proceedings

Description: Thirty five years ago, while in the neutron cross section group led by Robert Howerton at LLNL, the concept of reconstructing a three dimensional spatial distribution from its projections onto two dimensional planes was tackled by some of us using three now well known methods: simple back projection, Fourier projection theorem methods and iterative least squares algebraic reconstruction. The method of iterative least squares reconstruction was implemented on patient data in the early 1970s usin… more
Date: November 10, 2003
Creator: Azevedo, S
Partner: UNT Libraries Government Documents Department
open access

Molecular Basis for Enzymatic Sulfite Oxidation -- HOW THREE CONSERVED ACTIVE SITE RESIDUES SHAPE ENZYME ACTIVITY

Description: Sulfite dehydrogenases (SDHs) catalyze the oxidation and detoxification of sulfite to sulfate, a reaction critical to all forms of life. Sulfite-oxidizing enzymes contain three conserved active site amino acids (Arg-55, His-57, and Tyr-236) that are crucial for catalytic competency. Here we have studied the kinetic and structural effects of two novel and one previously reported substitution (R55M, H57A, Y236F) in these residues on SDH catalysis. Both Arg-55 and His-57 were found to have key rol… more
Date: November 10, 2008
Creator: Bailey, Susan; Rapson, Trevor; Johnson-Winters, Kayunta; Astashkin, Andrei; Enemark, John & Kappler, Ulrike
Partner: UNT Libraries Government Documents Department
open access

Lepton Universality, |V(Us)| and Search for Second Class Current in Tau Decays

Description: Several hundred million {tau} decays have been studied with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. Recent results on Charged Current Lepton Universality and two independent measurements of |V{sub us}| using {tau}{sup -} {yields} e{sup -}{bar {nu}}{sub e}{nu}{sub {tau}}, {mu}{sup -}{bar {nu}}{sub {mu}}{nu}{sub {tau}}, {pi}{sup -}{nu}{sub {tau}}, K{sup -} {nu}{sub {tau}} and K{sub S}{sup 0}{pi}{sup -} {nu}{sub {tau}} decays, and a s… more
Date: November 10, 2011
Creator: Banerjee, Swagato
Partner: UNT Libraries Government Documents Department
open access

Target input requirement for heavy ion fusion

Description: The requirements a heavy ion accelerator must meet in order to initiate practical thermonuclear microexplosions are summarized. Particular emphasis is given to the question of maximum allowable ion energy.
Date: November 10, 1977
Creator: Bangerter, R.O.
Partner: UNT Libraries Government Documents Department
open access

Leptonic B Decays at BaBar

Description: We will present the most recent results on leptonic B decays B{sup {+-}(0)} {yields} K*{sup {+-}(0)}{nu}{bar {nu}} and B{sup {+-}} {yields} {mu}{sup {+-}}{nu}, based on the data collected by the BaBar detector at PEP-II, an asymmetric e{sup +}e{sup -} collider at the center of mass energy of the {Upsilon}(4S) resonance. Rare B decays have always been a standard probe for New Physics (NP) searches. The very low Standard Model (SM) rate of these decays often make them unaccessible with the presen… more
Date: November 10, 2011
Creator: Baracchini, Elisabetta
Partner: UNT Libraries Government Documents Department
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Systems engineering applied to integrated safety management for high consequence facilities

Description: Integrated Safety Management is a concept that is being actively promoted by the U.S. Department of Energy as a means of assuring safe operation of its facilities. The concept involves the integration of safety precepts into work planning rather than adjusting for safe operations after defining the work activity. The system engineering techniques used to design an integrated safety management system for a high consequence research facility are described. An example is given to show how the conc… more
Date: November 10, 1998
Creator: Barter, R & Morais, B
Partner: UNT Libraries Government Documents Department
open access

Visualizing systems engineering data with Java

Description: Systems Engineers are required to deal with complex sets of data. To be useful, the data must be managed effectively, and presented in meaningful terms to a wide variety of information consumers. Two software patterns are presented as the basis for exploring the visualization of systems engineering data. The Model, View, Controller pattern defines an information management system architecture. The Entity, Relation, Attribute pattern defines the information model. MVC �Views� then form the basis… more
Date: November 10, 1998
Creator: Barter, R & Vinzant, A
Partner: UNT Libraries Government Documents Department
open access

Materials technology applied to nuclear accelerator targets

Description: The continuing requests for both shaped and flat, very low areal density metal foils have led to the development of metallurgical quality, high strength products. Intent of this paper is to show methods of forming structures on various substrates using periodic vapor interruptions, alternating anodes, and mechanical peening to alter otherwise unacceptable grain morphology which both lowers tensile strength and causes high stresses in thin films. The three technologies, physical vapor deposition… more
Date: November 10, 1986
Creator: Barthell, Barry L.
Partner: UNT Libraries Government Documents Department
open access

Energy generation in convective shells of low mass, low metallicity stars

Description: We report on the non-negligible energy generation from the {sup 13}C neutron source and neutron capture reactions in low mass, low metallicity AGB stars. About 10{sup 4} L{sub {circle dot}} are generated within the thermal pulse convective shell by the combination of the {sup 13}C({alpha}, n){sup 16}O rate and the sum of the Y(Z,A)(n,{gamma})Y(Z,A + 1) reactions and beta decays. The inclusion of this energy source in an AGB thermal pulse evolution is shown to alter the evolution of the convecti… more
Date: November 10, 1989
Creator: Bazan, G. (Illinois Univ., Urbana, IL (USA). Dept. of Astronomy) & Lattanzio, J.C. (Lawrence Livermore National Lab., CA (USA))
Partner: UNT Libraries Government Documents Department
open access

Exploring the Outer Solar System with the ESSENCE Supernova Survey

Description: We report the discovery and orbital determination of 14 trans-Neptunian objects (TNOs) from the ESSENCE Supernova Survey difference imaging data set. Two additional objects discovered in a similar search of the SDSS-II Supernova Survey database were recovered in this effort. ESSENCE repeatedly observed fields far from the solar system ecliptic (-21{sup o} < {beta} < -5{sup o}), reaching limiting magnitudes per observation of I {approx} 23.1 and R {approx} 23.7. We examine several of the n… more
Date: November 10, 2011
Creator: Becker, A. C.; Arraki, K.; Kaib, N. A.; Wood-Vasey, W. M.; Aguilera, C.; Blackman, J. W. et al.
Partner: UNT Libraries Government Documents Department
open access

2-MV electrostatic quadrupole injector for heavy-ion fusion

Description: High current and low emittance are principal requirements for heavy-ion injection into a linac driver for inertial fusion energy. An electrostatic quadrupole (ESQ) injector is capable of providing these high charge density and low emittance beams. We have modified the existing 2-MV Injector to reduce beam emittance and to double the pulse length. We characterize the beam delivered by the modified injector to the High Current Transport Experiment (HCX) and the effects of finite rise time of the … more
Date: November 10, 2004
Creator: Bieniosek, F. M.; Celata, C. M.; Henestroza, E.; Kwan, J. W.; Prost, L. & Seidl, P. A.
Partner: UNT Libraries Government Documents Department
open access

"Burst-like" Characteristics of the delta/alpha-prime Phase Transformation in Pu-Ga Alloys

Description: The {delta} to {alpha}' phase transformation in Pu-Ga alloys is intriguing for both scientific and technological reasons. On cooling, the ductile fcc d-phase transforms martensitically to the brittle monoclinic {alpha}'-phase at approximately -120 C (depending on composition). This exothermic transformation involves a 20% volume contraction and a significant increase in resistivity. The reversion of {alpha}' to {delta} involves a large temperature hysteresis beginning just above room temperatur… more
Date: November 10, 2003
Creator: Blobaum, K; Krenn, C; Haslam, J; Wall, M & Schwartz, A
Partner: UNT Libraries Government Documents Department
open access

A streamlined method for chiral fermions on the lattice

Description: We discussed the use of renormalization counterterms to restore the chiral gauge symmetry in a lattice theory of Wilson fermions. We show that a large class of counterterms can be implemented automatically by making a simple modification to the fermion determinant.
Date: November 10, 1992
Creator: Bodwin, G.T. (Argonne National Lab., IL (United States). High Energy Physics Div.) & Kovacs, E.V. (Fermi National Accelerator Lab., Batavia, IL (United States))
Partner: UNT Libraries Government Documents Department
open access

A streamlined method for chiral fermions on the lattice

Description: We discussed the use of renormalization counterterms to restore the chiral gauge symmetry in a lattice theory of Wilson fermions. We show that a large class of counterterms can be implemented automatically by making a simple modification to the fermion determinant.
Date: November 10, 1992
Creator: Bodwin, Geoffrey T. & Kovacs, Eve V.
Partner: UNT Libraries Government Documents Department
open access

Piezoelectric Effects on the Optical Properties of GaN/Al(x)Ga(1-x)N Multiple Quantum Wells

Description: Piezoelectric effects on the optical properties of GaN/AlGaN multiple quantum wells (MQWS) have been investigated by picosecond time-resolved photoluminescence (PL) measurements. For MQWS with well thickness 30 and 40 the excitonic transition peak positions at 10 K in continuous wave (CW) spectra are red-shifted with respect to the GaN epilayer by 17 meV and 57 meV, respectively. The time-resolved PL spectra of the 30 and 40 well MQWS reveal that the excitonic transition is in fact blue-shifted… more
Date: November 10, 1998
Creator: Botchkarev, A.; Chow, W. W.; Jiang, H. X.; Kim, H. S.; Lin, J. Y. & Morkoc, H.
Partner: UNT Libraries Government Documents Department
open access

Production of BaBar Skimmed Analysis Datasets Using the Grid

Description: The BABAR Collaboration, based at Stanford Linear Accelerator Center (SLAC), Stanford, US, has been performing physics reconstruction, simulation studies and data analysis for 8 years using a number of compute farms around the world. Recent developments in Grid technologies could provide a way to manage the distributed resources in a single coherent structure. We describe enhancements to the BABAR experiment's distributed skimmed dataset production system to make use of European Grid resources … more
Date: November 10, 2011
Creator: Brew, C. A. J.; Wilson, F. F.; Castelli, G.; Adye, T.; Roethel, W.; Luppi, E. et al.
Partner: UNT Libraries Government Documents Department
open access

Hadron Optics in Three-Dimensional Invariant Coordinate Space from Deeply Virtual Compton Scattering

Description: The Fourier transform of the deeply virtual Compton scattering amplitude (DVCS) with respect to the skewness parameter {zeta} = Q{sup 2}/2p {center_dot} q can be used to provide an image of the target hadron in the boost-invariant variable {sigma}, the coordinate conjugate to light-front time {tau} = t + z/c. As an illustration, we construct a consistent covariant model of the DVCS amplitude and its associated generalized parton distributions using the quantum fluctuations of a fermion state at… more
Date: November 10, 2006
Creator: Brodsky, S J; Chakrabarti, D; Harindranath, A; Mukherjee, A & Vary, J P
Partner: UNT Libraries Government Documents Department
open access

Classical Rayleigh-Taylor instability experiments at Nova

Description: The evolution of the Rayleigh-Taylor (RT) instability at an embedded, or classical, interface is examined in a series of experiments at the Nova laserfacility .[reference for Nova] These experiments focused on the transition from the linear to nonlinear regimes for both single- and multimode initialperturbations. The development of a single mode at the embedded interface is compared to its evolution at an ablation front and the effect of ablativestabilization is experimentally demonstrated. The… more
Date: November 10, 1997
Creator: Budil, K. S.; Remington, B. A.; Weber, S. V.; Perry, T. S. & Peyser, T. A.
Partner: UNT Libraries Government Documents Department
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